fix(photostory): optimise the state update in photostory (#444)

* fix(photostory): optimise the state update

* fix(photostory): update right side image in carousel

client/src/components/photostory/Carousel.js

@@ -13,19 +13,15 @@ const Carousel = ({ content }) => {
   const classes = useStyles();
   const length = content.length;
 
-  const [left, setLeft] = useState(length - 1);
   const [current, setCurrent] = useState(0);
-  const [right, setRight] = useState(1);
+  const left = current === 0 ? length - 1 : current - 1;
+  const right = current === length - 1 ? 0 : current + 1;
 
   const nextSlide = () => {
-    setLeft(left === length - 1 ? 0 : left + 1);
     setCurrent(current === length - 1 ? 0 : current + 1);
-    setRight(right === length - 1 ? 0 : right + 1);
   };
   const prevSlide = () => {
-    setLeft(left === 0 ? length - 1 : left - 1);
     setCurrent(current === 0 ? length - 1 : current - 1);
-    setRight(right === 0 ? length - 1 : right - 1);
   };
 
   if (!Array.isArray(content) || content.length <= 0) {